This field is the single lowest per-interval delta value on the live, currently-updating stats object for FCoE frames that arrived on the wire but were discarded before being handed up to the Fibre Channel stack — the quietest interval seen across the retained collection history. This mainly matters as a sanity baseline — a DeltaMin of zero for droppedRx on this interface just confirms there were quiet intervals with none of this condition, while a DeltaMin well above zero would mean it never stopped happening even at its calmest. For example, a min of 2 frames would mean even the quietest retained interval for this interface still saw 2, hinting the condition never fully stopped.